A 3370-G FULL-TERM infant was born to a 23-year-old gravida 3, para 2 mother by elective cesarean section. The pregnancy was remarkable only for a routine obstetrical ultrasound at 33 weeks of gestation showing an intracranial lesion. A magnetic resonance (MR) scan of the mother's abdomen revealed a large posterior, midline intracranial fluid collection (Figure 1). At birth the baby had normal Apgar scores, a mature lung profile, normal weight, and normal results of physical examination. At 5 days of age an MR image of the brain was obtained, including an MR venogram, which demonstrated a hyperintense signal on T1 and T2 sequences between the leaves of the posterior falx cerebri. An MR venogram demonstrated nonvisualization of the straight sinus and multichannel venous drainage of the posterior one third of the superior sagittal sinus that extended along the periphery of the falx hematoma (Figure 2). The infant remained